1. Field of the Invention
The present invention relates to magnetic head sliders with a magnetic device for writing a signal to and/or reading a signal from a magnetic disk, and particularly to a magnetic head slider that reduces variations in flying height caused in particular by atmospheric pressure changes.
2. Description of the Related Art
PCT Japanese Translation Patent Publication No. 2003-515869 discloses various forms of disk-facing surfaces of magnetic head sliders.
A disk-facing surface of a magnetic head slider generally has a recessed area that is located at the lowest level and causes a negative pressure, and a raised surface that causes a positive pressure. Conventionally, the shapes of the recessed area and raised surface, the area ratio therebetween with respect to the magnetic disk, and the like are adjusted to achieve a stable flying position of the magnetic head slider.
The flying position of the magnetic head slider tends to become unstable due to a reduction in the amount of air inflow caused by, for example, changes in atmospheric pressure and a reduction in peripheral speed associated with the reduced size of the magnetic disk. However, PCT Japanese Translation Patent Publication No. 2003-515869 described above proposes no specific approach to stabilize the unstable flying position of the magnetic head slider caused by a reduction in the amount of air inflow.
In general, a raised surface that causes a positive pressure is provided on both the leading and trailing sides of a magnetic head slider. A raised surface on the trailing side is a magnetic device surface where a surface of a magnetic device is exposed, while a raised surface on the leading side is divided into the right and left sides, such as side rails 210 and 212 shown in FIG. 2 of PCT Japanese Translation Patent Publication No. 2003-515869. In FIG. 2 of this document, a cavity dam 230 is provided at a level lower than the side rails 210 and 212.
FIG. 2 of PCT Japanese Translation Patent Publication No. 2003-515869 shows a typical disk-facing surface on which a cavity (which is a negative pressure generating surface) 236 of a certain height is surrounded by rails, and a separate center pad 240 including a magnetic device is provided.
In this disk-facing surface, air from the leading side flows, before reaching the separate center pad 240, over an uneven surface, which is made up of the cavity dam 230, cavity 236, and the like with varying heights different from the height of the center pad 240. This uneven surface causes the air to be disturbed, causes the air to escape from the sides of the center pad 240, and so on. In addition, a reduction in the amount of air inflow due to atmospheric pressure changes or the like considerably reduces the amount of air that reaches the center pad 240, which causes a positive pressure, and thus reduces the flying height of the magnetic head slider.
Another disk-facing surface of a magnetic head slider disclosed in PCT Japanese Translation Patent Publication No. 2003-515869 is one in which, as shown in FIG. 8, a rail surface at the same height as a cavity dam 506 extends from the cavity dam 506 to a center rail 508. Specifically, in FIG. 8 of this document, a convex center-rail bearing surface 516 located at the highest level is provided as a positive pressure generating surface. Side rails 502 and 504 are also provided as positive pressure generating surfaces on the leasing side.
However, an experiment (described below in Comparative Example 1 in FIG. 7 of the present invention) revealed that, even with this structure shown in FIG. 8 of PCT Japanese Translation Patent Publication No. 2003-515869, the loss of air until it reached the center-rail bearing surface 516 was significant, and that the flying height of the magnetic head slider was greatly reduced by a reduction in the amount of air inflow due to atmospheric pressure changes or the like.